Material? Made of vegetable tanned full grain cowhide leather and suede inner cushion for non-slip, heavy-duty stitching and durable. Fit 1″ Swivels? Our shell holder sling can be adjustable from 33.5″ to 41.5. Both ends of the shoulder strap are 1 inch wide, suitable for most rifle swivels. 45 Long Colt, 7MM REM 6.8 SPC and. 410 shotgun bullets as well. 17 hmr Cartridge Holder. 12GA Shell holder Shotgun Slin. This sling is specially made for bullet models such as 12 Guage. Note that 20GA and 16GA are not available. 6GA Shell holder Shotgun Sling? Ing is specially made for bullet models such as 16 Guage. 20GA Shell holder Shotgun Sling? This sling is specially made for bullet models such as 20 Guage. Ded Leather ammo holder sling.